Injection molding machine spreader



` N. LESTER 2 sheets-sheet 1 Sept. 30, 1947. y

` v l INJECTIO Filed March 2o, 1944 [NVE NATHAN I 'ES sept. 3o, v1947.

N. LESTERA INJECTION MOLDIG MACHINE SPREADER 2 Sheets-Sheet 2 Filed March 20, 1944 INVENTOR NATHAN LESTER BY AQ ATTORQFLEYSCL7 been encountered patented ZSept. 30, 12947;

UNITED sTATEs `laixTlslfvr- [:oiflflcli INJECTION MOLDING MACHINE SPREDR Nathan Lester, Cleveland Heights, Ohio, assignor to Lester Engineering Company, Cleveland, AOhio, a corporation of Ohio Application March 20, 1944, Serial No. 527,206

The present invention relates to that particular part of an injection molding or pressure casting machine wherein the material to be molded is subjected to heat and pressure to reduce it to the plasticized state, and then injected into the die or mold forming cavity. In order to reduce the cross-section of the plastic material for eiecting a rapid and uniform transmission of heat throughout the body of the material, the expedient has been heretofore hit upon of inserting a spreader (otherwise sometimes known in the art as a pineapple or torpedo) in the pressure cylinder.

Since it is desirable to heat all of the surfaces of the injection cylinder and of the spreader in order to effect the uniform and as eicient as possible heating action upon the plastic material, designers of such injection molding machine spreaders have heretofore been confronted with the problem of how to locate a heating element within the spreader, without materially aiecting the strength of the supporting elements vof the spreader, as well as providing means for easily assembling, removing and replacing the heating element, as occasion arises.

Further diiculties have also been encountered by workers in this particular art with regard to designing a spreader which does not oler too `great a resistance to the iiow of material through the passages which it forms. Diiiculty has also in properly anchoring or mounting the spreader in the injection cylinder with sufficient strength to enable it to withstand 4 Claims. (Cl. 18 30) al few of the various ways in which the principle Y of the invention may be employed.

outer end of the cylinder, whereby any stress or strain tending to displace the spreader from the injection cylinder is in the form of compressive I rather than shearing forces.

Still another object and advantage of my invention is to be found in the provision of radial supporting legs on the inner end of the spreader thereby maintaining the proper alignment and spacing of the spreader within the cylinder and further reinforcing the strength of the spreader mounting therein.

To the accomplishment of the foregoing and related ends, said invention then comprises the ,features hereinafter fully described and partic- V ularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but In s-aid annexed drawings: Fig.A l is a sectional View taken through an injection molding cylinder and spreader embodying the principle of my invention;

Figs. 2, 3, 4 and 5 are transverse sections taken along lines 2 2, 3 3, 4 4 and 5 5, respectively, of Fig. 1;

Fig. 6 is a perspective view of the body 0f ma- .terial alone in the lower portion of the injection Walls of the injection cylinder, thus presenting an annular passage of minimum resistance to ilow, together with a pair of passages which'make a right angle turn from suchannular passage, and merge with each other into the discharge nozzle passage located in the side Wall of the injection cylinder. This permits a heat element to be mounted within the spreader, and the spreader in turn to be held within the injection cylinder by means of an abutment closure plate on the cylinder and the injection nozzle, `and further illustrating the conformation and shape of the man terial flow passages formed by the spreader and cylinder; and

Fig. 7 is a partial sectional view, similar to that of Fig. 1 but showing a modified form of construction.

Now referring more particularly to the drawings, there is shown therein an injection cylinder body l which can suitably be assembled in an inljection molding machine such as that shown and described in by prior U. S. Patent No. 2,262,615, issued November 11, 1941. The cylinder I has an inner bore portion 2 in which the solid plunger A3 is adapted to reciprocate. In Fig. 1, the plunger 3 is shown at the innermost point of its lmovement within the bore 2. The cylinder body I also has an enlarged bore portion 4 merging with the bore 2. w.

The spreader comprises a cylindrical shank portion 5 whoseouter diameter is smaller than the inner diameter of the bore 4, thus forming an annular space or chamber between their respective surfaces.` The inner terminal end of the shank 5 converges to ,bullet shape or prolate form as indicated at, G. The bottom or outer end of the spreader is in the form of a cylindrical portion 'I which has a diameter substantially equal to the inner diameter of the bore 4, and hence ts snugly therein. An annular shoulder 8 may be provided on the bottommost, or outer end of the spreader and tted into a complementary recess in the end of the cylinder body I. An abutment orA closure plate 9 is, thenk fastened up.

against th'e'enc of the cylinder "l, such' as by,

means of 'th`e"` :a1o screws II),u and iholdsutl'le spreader firmly against the injection pressure which is exerted upon it and normally tends to expel the spreader out fromthe endv of the cylinder I. l

Radially projecting legs II, of generally ellipntical shape, the major axis'of which is' parallel to the axis of the cylinder bore 4, are mounted on the inner or upper end ofthe spreader 'shank' and fit against the cylindrical wall of the bore 4.

A discharge nozzleV I2, having the nozzle fitting I3, is mounted o nk the side of the cylinder I.V The passageV I4 inthe nozzle I2 communicates with an opening I5 in the cylinder 'I. This opening I5 is in alignment with theipoint oi juncture 'l5 of the two converging channels or passages I 'I and I'I which are formed in the surface of the cylin-f drical portion 'I of the spreader. As fully described in my prior Patent 2,262,615r the entire 5 zone corresponding to the extent of the spreader shank portion 5 (as indicated by the extra coil of heating wire at 23) than it does in the remaining portion of. thel spreader.

'The cilinder. l is, of baissa heated in. the cusl0 tomary manner by an electric, oil or steam, heating jacket. Thermocouple holes are provided at'23', 24, 25 and 26 for determining and aiding in the control of the temperatures maintained at the` respective zones. along the path of flow of the. matenitnroiigiithe injection cylinder.

The conformation of the material now passages formed by the above-described spreader and injection cylir'ider`A structure is further illustrated in of. Thus, the portion A represents the annular space between the shank portion 5 and the cylinder bore4. The portion Brepresents the discharge passage I4. The portions CC'represent the' conformation ofmaterial in the'passages Il and ITI', and the open portions yD and E are those which are occupied by the cylindrical portion 'I of the spreader in which the passages II and I1' are formed.. Thus, it will be seen that the material has a minimum impedance or resistance placed inits path, in its iiow from its full, relaylnder l With its attached rarrsis Swingabiysony/@1y thin cross-'semmai form A, to as rma; cismounted on the frame of the machine about an axis parallel to that of the cylinder so as to bring said nozzle fitting I3 into and out of operative molding position. When the nozzle fitting I3'V is thus operatively positioned the lower end of said cylinder is rmly supported by a jack screw 21.k

When the cylinder I` is swung so as to bringthe nozzle fitting I3 out of` operative molding posi'- tion, the lower end thereof is clear of` the jack Screw 2T and other parts" of the machine and is 49: terior of the plunger 3l). rPhe lower or remainreadily accessible for replailg or servicing of the spreaderor of thev heating element therein.

The jack screw 21 is adjustably butrmly secured to the frame of the machine' and is operative to firmly support'the spreader againstmovement and also to absorb 'the load caused by the pressure of the molding material within the ycyl-- inder tending to expel the spreader from therein, which load otherwise might overstress the bolts III which hold the' plate Si` on the cylinden The engagement between flange 8 of the spreader and` the internal shoulder in the cylinder against which it bears provides a seal to prevent the molding material from creeping downwardly along the cylinder wall between the cylinder wall and the head1 of the spreader into the passage 2l in the plate 9 and into contact withv the lead wires 22 of the heating element I .9.

As will be seen by reference to the cross-seo. tional Figures 3-5, incl., the passages I'I and IIr each extend 180 around thel periphery of the cylindrical portion 1., beingy substantially'contiguous with each other atthe points I8,A and I8. The thickness or depthl of the passages II,v and I1.' at this point is substantially equal tothe thickness or depth ofthe space between the shank portion 5` and` the ,cylinder bore 4. Then, as the4 passages 'II and I1' converge in Width, they coreA respondingly become greaterA in,l thickness Q or depthuntilmergingl at the point II.

A heating cartridgaindicated generally at ISI,

' charge from thefnozzle portionB.

In the modiiied form of construction shown in Fig. 7, an annular plunger is employed inthe cylinder I', in place of the solid plunger 3. In

i3? this instance, the spreader shank portion 5" does not termin'atejust above the supporting ribs II" (or alternatively just below the point of innermost travel of the plunger), but extends, in the form of the cylindrical portion 3|, into thehollow ining portion of the spreader5 and of the cylinder I', of course, remains the same as previously described in connection with Figs. 1-6, inclusive. It will thus be seen that the spreader constructed according to my above-describedinvention can be relatively simplyand economically made in the form ofa single piece of metal, and that. it does not require the relatively expensive and time-con mrlsuming machining :methods involved` the. drilling of a plurality of` small bores and internai passages. All ofr' "the material contacting surfaces in my spreader can bev machined and formed by exterior r'iperations.y

Otherjrnlodes of applyingthe principle of the I therefore particularlypointout and distinctlyA claim asiny invention:

1. The combination with the injection cylinder of a` pressuremolding. machine, such cylinder having -a lateral discharge opening adjacent one G15-end thereof, of a spreader comprising a head closely fitted withizrsuch cylinder end and1ex tending tola'pointbeyond suchopem'ng and a shankfof smallerdiameter than the bore fof said cylinder'projecting from said head into the lat- 70, te r, saidhe'ad being formed with plural channels leading from the space .between said shankand cylinder bore to, such discharge opening, such` Channels. being, Of. progressively "decreasing Width towarl'dflsilch disch@ Opening and thegportiorls Widthbngl Substantially equal to the diameter of and in register with such discharge opening.

2. The combination with the injection cylinder of a pressure molding machine, such cylinder having a lateral discharge opening adjacent one end thereof, of a spreader comprising a head closely fitted within such cylinder end and extending to a point beyond such opening and a shank of smaller diameter than the bore of said cylinder projecting from said head into the latter, said head being formed with plural channels leading from the space between said shank and cylinder bore to such discharge opening, such channels being of progressively decreasing width and increasing depth toward such discharge opening and the portions thereof of minimum width being substantially equal to the diameter of and in register with such discharge opening, such increasing depth of the channels compensating for the decrease in the cross-section areas thereof by the decreasing width thereof.

3. The combination with the injection cylinder of a pressure molding machine, such cylinder havlng a lateral discharge opening adjacent one end thereof, of a spreader comprising a head closely tted within such cylinder end and extending to a point beyond such opening and a shank of smaller diameter than the bore of said cylinder projecting from said head into the latter, said head being formed leading from the space between said shank and cylinder bore to such discharge opening, such channels being symmetrical about the longitudinal axis of the spreader for a portion of their extent and of progressively decreasing Width toward such discharge opening and the portions with plural channels' thereof of minimum width being substantially cylinder bore to such discharge opening, such channels :being of progressively decreasing width toward such discharge opening and the portions thereof of minimum width being substantially equal to the diameter of and in register with such discharge opening, said head being formed with a radial iin opposite such discharge opening for diverting the liow of molding material from such channels directly into such discharge opening.

NATHAN LESTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,202,140 Burroughs May 28, 1940 2,308,867 Dlnzl Jan. 19, 1943 2,309,496 Bird et al. Jan. 26, 1943 2,309,943 Ernst Feb. 2, 1943 1,939,041 Cherry Dec. 12, 1933 

